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Zheng Z, Zong Y, Ma Y, Tian Y, Pang Y, Zhang C, Gao J. Glucagon-like peptide-1 receptor: mechanisms and advances in therapy. Signal Transduct Target Ther 2024; 9:234. [PMID: 39289339 PMCID: PMC11408715 DOI: 10.1038/s41392-024-01931-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 06/17/2024] [Accepted: 07/16/2024] [Indexed: 09/19/2024] Open
Abstract
The glucagon-like peptide-1 (GLP-1) receptor, known as GLP-1R, is a vital component of the G protein-coupled receptor (GPCR) family and is found primarily on the surfaces of various cell types within the human body. This receptor specifically interacts with GLP-1, a key hormone that plays an integral role in regulating blood glucose levels, lipid metabolism, and several other crucial biological functions. In recent years, GLP-1 medications have become a focal point in the medical community due to their innovative treatment mechanisms, significant therapeutic efficacy, and broad development prospects. This article thoroughly traces the developmental milestones of GLP-1 drugs, from their initial discovery to their clinical application, detailing the evolution of diverse GLP-1 medications along with their distinct pharmacological properties. Additionally, this paper explores the potential applications of GLP-1 receptor agonists (GLP-1RAs) in fields such as neuroprotection, anti-infection measures, the reduction of various types of inflammation, and the enhancement of cardiovascular function. It provides an in-depth assessment of the effectiveness of GLP-1RAs across multiple body systems-including the nervous, cardiovascular, musculoskeletal, and digestive systems. This includes integrating the latest clinical trial data and delving into potential signaling pathways and pharmacological mechanisms. The primary goal of this article is to emphasize the extensive benefits of using GLP-1RAs in treating a broad spectrum of diseases, such as obesity, cardiovascular diseases, non-alcoholic fatty liver disease (NAFLD), neurodegenerative diseases, musculoskeletal inflammation, and various forms of cancer. The ongoing development of new indications for GLP-1 drugs offers promising prospects for further expanding therapeutic interventions, showcasing their significant potential in the medical field.
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Affiliation(s)
- Zhikai Zheng
- Department of Orthopaedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
- Institute of Microsurgery on Extremities, and Department of Orthopedic Surgery, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
| | - Yao Zong
- Centre for Orthopaedic Research, Medical School, The University of Western Australia, Nedlands, WA, 6009, Australia
| | - Yiyang Ma
- Department of Orthopaedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
- Institute of Microsurgery on Extremities, and Department of Orthopedic Surgery, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
| | - Yucheng Tian
- Department of Orthopaedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
- Institute of Microsurgery on Extremities, and Department of Orthopedic Surgery, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
| | - Yidan Pang
- Department of Orthopaedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
- Institute of Microsurgery on Extremities, and Department of Orthopedic Surgery, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
| | - Changqing Zhang
- Department of Orthopaedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
- Institute of Microsurgery on Extremities, and Department of Orthopedic Surgery, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
| | - Junjie Gao
- Department of Orthopaedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China.
- Institute of Microsurgery on Extremities, and Department of Orthopedic Surgery, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China.
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Reed J, Bain SC, Kanamarlapudi V. The Regulation of Metabolic Homeostasis by Incretins and the Metabolic Hormones Produced by Pancreatic Islets. Diabetes Metab Syndr Obes 2024; 17:2419-2456. [PMID: 38894706 PMCID: PMC11184168 DOI: 10.2147/dmso.s415934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 05/07/2024] [Indexed: 06/21/2024] Open
Abstract
In healthy humans, the complex biochemical interplay between organs maintains metabolic homeostasis and pathological alterations in this process result in impaired metabolic homeostasis, causing metabolic diseases such as diabetes and obesity, which are major global healthcare burdens. The great advancements made during the last century in understanding both metabolic disease phenotypes and the regulation of metabolic homeostasis in healthy individuals have yielded new therapeutic options for diseases like type 2 diabetes (T2D). However, it is unlikely that highly desirable more efficacious treatments will be developed for metabolic disorders until the complex systemic regulation of metabolic homeostasis becomes more intricately understood. Hormones produced by pancreatic islet beta-cells (insulin) and alpha-cells (glucagon) are pivotal for maintaining metabolic homeostasis; the activity of insulin and glucagon are reciprocally correlated to achieve strict control of glucose levels (normoglycaemia). Metabolic hormones produced by other pancreatic islet cells and incretins produced by the gut are also crucial for maintaining metabolic homeostasis. Recent studies highlighted the incomplete understanding of metabolic hormonal synergism and, therefore, further elucidation of this will likely lead to more efficacious treatments for diseases such as T2D. The objective of this review is to summarise the systemic actions of the incretins and the metabolic hormones produced by the pancreatic islets and their interactions with their respective receptors.
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Affiliation(s)
- Joshua Reed
- Institute of Life Science, Medical School, Swansea University, Swansea, SA2 8PP, UK
| | - Stephen C Bain
- Institute of Life Science, Medical School, Swansea University, Swansea, SA2 8PP, UK
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Guo W, Gao L, Mo H, Deng H, Zhao Y, Xu G. Mechano-sensor Piezo1 inhibits glucagon production in pancreatic α-cells. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167185. [PMID: 38653360 DOI: 10.1016/j.bbadis.2024.167185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 04/12/2024] [Accepted: 04/15/2024] [Indexed: 04/25/2024]
Abstract
OBJECTIVE Glucagon is a critical hormone regulating glucose metabolism. It stimulates the liver to release glucose under low blood sugar conditions, thereby maintaining blood glucose stability. Excessive glucagon secretion and hyperglycemia is observed in individuals with diabetes. Precise modulation of glucagon is significant to maintain glucose homeostasis. Piezo1 is a mechanosensitive ion channel capable of converting extracellular mechanical forces into intracellular signals, thus regulating hormonal synthesis and secretion. This study aims to investigate the role of Piezo1 in regulating glucagon production in α cells. METHODS The effects of Piezo1 on glucagon production were examined in normal- or high-fat diet fed α cell-specific Piezo1 knockout mice (Gcg-Piezo1-/-), and the murine pancreatic α cell line αTC1-6. Expression of Proglucagon was investigated by real-time PCR and western blotting. Plasma glucagon and insulin were detected by enzyme immunoassay. RESULTS Under both normal- and high-fat diet conditions, Gcg-Piezo1-/- mice exhibited increased pancreatic α cell proportion, hyperglucagonemia, impaired glucose tolerance, and activated pancreatic mTORC1 signaling. Activation of Piezo1 by its agonist Yoda1 or overexpression of Piezo1 led to decreased glucagon synthesis and suppressed mTOR signaling pathway in αTC1-6 cells. Additionally, the levels of glucagon in the medium were also reduced. Conversely, knockdown of Piezo1 produced opposite effects. CONCLUSION Our study uncovers the regulatory role of the Piezo1 ion channel in α cells. Piezo1 influences glucagon production by affecting mTOR signaling pathway.
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Affiliation(s)
- Wenying Guo
- Department of Physiology, School of Medicine, Jinan University, 601 Huangpu Avenue West, Tianhe District, Guangzhou, Guangdong 510632, China
| | - Luyang Gao
- Department of Physiology, School of Medicine, Jinan University, 601 Huangpu Avenue West, Tianhe District, Guangzhou, Guangdong 510632, China
| | - Haocong Mo
- Department of Physiology, School of Medicine, Jinan University, 601 Huangpu Avenue West, Tianhe District, Guangzhou, Guangdong 510632, China
| | - Handan Deng
- Department of Physiology, School of Medicine, Jinan University, 601 Huangpu Avenue West, Tianhe District, Guangzhou, Guangdong 510632, China
| | - Yawen Zhao
- Department of Physiology, School of Medicine, Jinan University, 601 Huangpu Avenue West, Tianhe District, Guangzhou, Guangdong 510632, China
| | - Geyang Xu
- Department of Physiology, School of Medicine, Jinan University, 601 Huangpu Avenue West, Tianhe District, Guangzhou, Guangdong 510632, China; Key Laboratory of Viral Pathogenesis & Infection Prevention and Control (Jinan University), Ministry of Education, Guangzhou 510632, Guangdong, China.
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Nagai H, Nagai LAE, Tasaki S, Nakato R, Umetsu D, Kuranaga E, Miura M, Nakajima Y. Nutrient-driven dedifferentiation of enteroendocrine cells promotes adaptive intestinal growth in Drosophila. Dev Cell 2023; 58:1764-1781.e10. [PMID: 37689060 DOI: 10.1016/j.devcel.2023.08.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 05/05/2023] [Accepted: 08/16/2023] [Indexed: 09/11/2023]
Abstract
Post-developmental organ resizing improves organismal fitness under constantly changing nutrient environments. Although stem cell abundance is a fundamental determinant of adaptive resizing, our understanding of its underlying mechanisms remains primarily limited to the regulation of stem cell division. Here, we demonstrate that nutrient fluctuation induces dedifferentiation in the Drosophila adult midgut to drive adaptive intestinal growth. From lineage tracing and single-cell RNA sequencing, we identify a subpopulation of enteroendocrine (EE) cells that convert into functional intestinal stem cells (ISCs) in response to dietary glucose and amino acids by activating the JAK-STAT pathway. Genetic ablation of EE-derived ISCs severely impairs ISC expansion and midgut growth despite the retention of resident ISCs, and in silico modeling further indicates that EE dedifferentiation enables an efficient increase in the midgut cell number while maintaining epithelial cell composition. Our findings identify a physiologically induced dedifferentiation that ensures ISC expansion during adaptive organ growth in concert with nutrient conditions.
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Affiliation(s)
- Hiroki Nagai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan; Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, Miyagi 980-0845, Japan.
| | | | - Sohei Tasaki
- Graduate School of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
| | - Ryuichiro Nakato
- Institute for Quantitative Biosciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Daiki Umetsu
- Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-0845, Japan; Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Erina Kuranaga
- Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-0845, Japan
| | - Masayuki Miura
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yuichiro Nakajima
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan; Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, Miyagi 980-0845, Japan; Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-0845, Japan.
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Chen X, Merovci A, DeFronzo RA, Tripathy D. Chronic physiologic hyperglycemia impairs insulin-mediated suppression of plasma glucagon concentration in healthy humans. Metabolism 2023; 142:155512. [PMID: 36746320 DOI: 10.1016/j.metabol.2023.155512] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 01/22/2023] [Accepted: 01/30/2023] [Indexed: 02/05/2023]
Abstract
BACKGROUND AND AIMS Hyperglucagonemia is a characteristic feature of type 2 diabetes mellitus (T2DM). We examined the effect of chronic (48-72 h) physiologic increase (+50 mg/dl) in plasma glucose concentration on suppression of plasma glucagon concentration by insulin and by hyperglycemia in normal glucose tolerance (NGT) individuals. MATERIALS AND METHODS Study One: 16 NGT subjects received OGTT and 3-step hyperinsulinemic (10, 20, 40 mU/m2·min) euglycemic clamp before and after 48 hour glucose infusion to increase plasma glucose by ~50 mg/dl. Study Two: 20 NGT subjects received OGTT and 2-step hyperglycemic (+125 and + 300 mg/dl) clamp before and after 72 hour glucose infusion. Plasma insulin, C-peptide and glucagon concentrations were measured during OGTT, euglycemic hyperinsulinemic and hyperglycemic clamps. Ratio of plasma glucagon/insulin was used as an index of insulin-mediated suppression of glucagon secretion. RESULTS During all 3 insulin clamp steps (Study 1), plasma glucagon concentration was increased compared to baseline study, and plasma glucagon/insulin ratio was significantly reduced by 24 % (p < 0.05). The rate of insulin-stimulated glucose disposal was inversely correlated with plasma glucagon/insulin ratio (r = -0.44, p < 0.05) and with glucagon AUC (r = -0.48, p < 0.05). During the 2-step hyperglycemic clamp (Study 2) plasma glucagon was similar before and after 72 h of glucose infusion; however, glucagon/insulin ratio was significantly reduced (p < 0.05). Incremental area under plasma insulin curve during the first (r = -0.74, p < 0.001) and second (r = -0.85, p < 0.001) hyperglycemic clamp steps was strongly and inversely correlated with plasma glucagon/insulin ratio. CONCLUSION Sustained (48-72 h) physiologic hyperglycemia (+50 mg/dl) caused whole body insulin resistance and impaired insulin-mediated suppression of glucagon secretion, suggesting a role for glucotoxicity in development of hyperglucagonemia in T2DM.
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Affiliation(s)
- Xi Chen
- Department of Medicine, Diabetes Division, University of Texas Health Science Center, San Antonio, TX, USA
| | - Aurora Merovci
- Department of Medicine, Diabetes Division, University of Texas Health Science Center, San Antonio, TX, USA
| | - Ralph A DeFronzo
- Department of Medicine, Diabetes Division, University of Texas Health Science Center, San Antonio, TX, USA; Audie L. Murphy VA Hospital, South Texas Veterans Heath Care System, San Antonio, TX, USA
| | - Devjit Tripathy
- Department of Medicine, Diabetes Division, University of Texas Health Science Center, San Antonio, TX, USA; Audie L. Murphy VA Hospital, South Texas Veterans Heath Care System, San Antonio, TX, USA.
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The gut hormone Allatostatin C/Somatostatin regulates food intake and metabolic homeostasis under nutrient stress. Nat Commun 2022; 13:692. [PMID: 35121731 PMCID: PMC8816919 DOI: 10.1038/s41467-022-28268-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 01/18/2022] [Indexed: 12/13/2022] Open
Abstract
AbstractThe intestine is a central regulator of metabolic homeostasis. Dietary inputs are absorbed through the gut, which senses their nutritional value and relays hormonal information to other organs to coordinate systemic energy balance. However, the gut-derived hormones affecting metabolic and behavioral responses are poorly defined. Here we show that the endocrine cells of the Drosophila gut sense nutrient stress through a mechanism that involves the TOR pathway and in response secrete the peptide hormone allatostatin C, a Drosophila somatostatin homolog. Gut-derived allatostatin C induces secretion of glucagon-like adipokinetic hormone to coordinate food intake and energy mobilization. Loss of gut Allatostatin C or its receptor in the adipokinetic-hormone-producing cells impairs lipid and sugar mobilization during fasting, leading to hypoglycemia. Our findings illustrate a nutrient-responsive endocrine mechanism that maintains energy homeostasis under nutrient-stress conditions, a function that is essential to health and whose failure can lead to metabolic disorders.
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Asadi F, Dhanvantari S. Pathways of Glucagon Secretion and Trafficking in the Pancreatic Alpha Cell: Novel Pathways, Proteins, and Targets for Hyperglucagonemia. Front Endocrinol (Lausanne) 2021; 12:726368. [PMID: 34659118 PMCID: PMC8511682 DOI: 10.3389/fendo.2021.726368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 09/13/2021] [Indexed: 12/15/2022] Open
Abstract
Patients with diabetes mellitus exhibit hyperglucagonemia, or excess glucagon secretion, which may be the underlying cause of the hyperglycemia of diabetes. Defective alpha cell secretory responses to glucose and paracrine effectors in both Type 1 and Type 2 diabetes may drive the development of hyperglucagonemia. Therefore, uncovering the mechanisms that regulate glucagon secretion from the pancreatic alpha cell is critical for developing improved treatments for diabetes. In this review, we focus on aspects of alpha cell biology for possible mechanisms for alpha cell dysfunction in diabetes: proglucagon processing, intrinsic and paracrine control of glucagon secretion, secretory granule dynamics, and alterations in intracellular trafficking. We explore possible clues gleaned from these studies in how inhibition of glucagon secretion can be targeted as a treatment for diabetes mellitus.
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Affiliation(s)
- Farzad Asadi
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
- Program in Metabolism and Diabetes, Lawson Health Research Institute, London, ON, Canada
| | - Savita Dhanvantari
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
- Program in Metabolism and Diabetes, Lawson Health Research Institute, London, ON, Canada
- Imaging Research Program, Lawson Health Research Institute, London, ON, Canada
- Department of Medical Biophysics, Western University, London, ON, Canada
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Zeigerer A, Sekar R, Kleinert M, Nason S, Habegger KM, Müller TD. Glucagon's Metabolic Action in Health and Disease. Compr Physiol 2021; 11:1759-1783. [PMID: 33792899 PMCID: PMC8513137 DOI: 10.1002/cphy.c200013] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Discovered almost simultaneously with insulin, glucagon is a pleiotropic hormone with metabolic action that goes far beyond its classical role to increase blood glucose. Albeit best known for its ability to directly act on the liver to increase de novo glucose production and to inhibit glycogen breakdown, glucagon lowers body weight by decreasing food intake and by increasing metabolic rate. Glucagon further promotes lipolysis and lipid oxidation and has positive chronotropic and inotropic effects in the heart. Interestingly, recent decades have witnessed a remarkable renaissance of glucagon's biology with the acknowledgment that glucagon has pharmacological value beyond its classical use as rescue medication to treat severe hypoglycemia. In this article, we summarize the multifaceted nature of glucagon with a special focus on its hepatic action and discuss the pharmacological potential of either agonizing or antagonizing the glucagon receptor for health and disease. © 2021 American Physiological Society. Compr Physiol 11:1759-1783, 2021.
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Affiliation(s)
- Anja Zeigerer
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Revathi Sekar
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Maximilian Kleinert
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- Institute for Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Shelly Nason
- Comprehensive Diabetes Center, Department of Medicine - Endocrinology, Diabetes & Metabolism, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Kirk M. Habegger
- Comprehensive Diabetes Center, Department of Medicine - Endocrinology, Diabetes & Metabolism, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Timo D. Müller
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- Institute for Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, Eberhard Karls University Hospitals and Clinics, Tübingen, Germany
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Kumar U, Singh S. Role of Somatostatin in the Regulation of Central and Peripheral Factors of Satiety and Obesity. Int J Mol Sci 2020; 21:ijms21072568. [PMID: 32272767 PMCID: PMC7177963 DOI: 10.3390/ijms21072568] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/29/2020] [Accepted: 04/02/2020] [Indexed: 02/06/2023] Open
Abstract
Obesity is one of the major social and health problems globally and often associated with various other pathological conditions. In addition to unregulated eating behaviour, circulating peptide-mediated hormonal secretion and signaling pathways play a critical role in food intake induced obesity. Amongst the many peptides involved in the regulation of food-seeking behaviour, somatostatin (SST) is the one which plays a determinant role in the complex process of appetite. SST is involved in the regulation of release and secretion of other peptides, neuronal integrity, and hormonal regulation. Based on past and recent studies, SST might serve as a bridge between central and peripheral tissues with a significant impact on obesity-associated with food intake behaviour and energy expenditure. Here, we present a comprehensive review describing the role of SST in the modulation of multiple central and peripheral signaling molecules. In addition, we highlight recent progress and contribution of SST and its receptors in food-seeking behaviour, obesity (orexigenic), and satiety (anorexigenic) associated pathways and mechanism.
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He S, Le NA, Ramirez-Zea M, Martorell R, Narayan KMV, Stein AD. Leptin partially mediates the association between early-life nutritional supplementation and long-term glycemic status among women in a Guatemalan longitudinal cohort. Am J Clin Nutr 2020; 111:804-813. [PMID: 32069352 PMCID: PMC7138657 DOI: 10.1093/ajcn/nqaa001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 01/01/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Early-life exposure to improved nutrition is associated with decreased risk of diabetes but increased risk of obesity. Leptin positively correlates with adiposity and has glucose-lowering effects, thus it may mediate the association of early-life nutrition and long-term glycemic status. OBJECTIVES We aimed to investigate the role of leptin in the differential association between early-life nutrition and the risks of obesity and diabetes. METHODS We analyzed data from a Guatemalan cohort who were randomly assigned at the village level to receive nutritional supplements as children. We conducted mediation analysis to examine the role of leptin in the associations of early-life nutrition and adult cardiometabolic outcomes. RESULTS Among 1112 study participants aged (mean ± SD) 44.1 ± 4.2 y, 60.6% were women. Cardiometabolic conditions were common: 40.2% of women and 19.4% of men were obese, and 53.1% of women and 41.0% of men were hyperglycemic or diabetic. Median (IQR) leptin concentration was 15.2 ng/mL (10.2-17.3 ng/mL) in women and 2.7 ng/mL (1.3-5.3 ng/mL) in men. Leptin was positively correlated with BMI (Spearman's ρ was 0.6 in women, 0.7 in men). Women exposed to improved nutrition in early life had 2.8-ng/mL (95% CI: 0.3, 5.3 ng/mL) higher leptin and tended to have lower fasting glucose (-0.8 mmol/L; -1.8, 0.2 mmol/L, nonsignificant) than unexposed women. There were no significant differences in leptin (-0.7 ng/mL; -2.1, 0.8 ng/mL) or fasting glucose (0.2 mmol/L; -0.5, 0.9 mmol/L) in men exposed to improved nutrition in early life compared with unexposed men. Leptin mediated 34.9% of the pathway between early-life nutrition and fasting glucose in women. The mediation in women was driven by improved pancreatic β-cell function. We did not observe the mediation effect in men. CONCLUSIONS Leptin mediated the glucose-lowering effect of early-life nutrition in women but not in men.
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Affiliation(s)
- Siran He
- Nutrition and Health Sciences Program, Laney Graduate School, Emory University, Atlanta, GA, USA
| | - Ngoc-Anh Le
- Biomarker Core Laboratory, Foundation for Atlanta Veterans Education and Research, Atlanta Veterans Affairs Medical Center, Atlanta, GA, USA
| | - Manuel Ramirez-Zea
- INCAP Research Center for the Prevention of Chronic Diseases, Institute of Nutrition of Central America and Panama, Guatemala City, Guatemala
| | | | | | - Aryeh D Stein
- Rollins School of Public Health, Emory University, Atlanta, GA, USA,Address correspondence to ADS (e-mail: )
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El K, Campbell JE. The role of GIP in α-cells and glucagon secretion. Peptides 2020; 125:170213. [PMID: 31785304 PMCID: PMC7580028 DOI: 10.1016/j.peptides.2019.170213] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 11/22/2019] [Accepted: 11/25/2019] [Indexed: 02/07/2023]
Abstract
Glucose-dependent insulinotropic polypeptide (GIP) is an intestinally derived peptide that is secreted in response to feeding. The GIP receptor (GIPR) is expressed in many cell types involved in the regulation of metabolism, including α- and β-cells. Glucagon and insulin exert tremendous control over glucose metabolism. Thus, GIP action in islets strongly dictates metabolic control in the postprandial state. Loss of GIPR activity in β-cells is a characteristic of type 2 diabetes (T2D) which associates with reduced postprandial insulin secretion and hyperglycemia. Less is known about GIPR activity in α-cells or the control of glucagon secretion. GIP stimulates glucagon secretion in a glucose-dependent manner in healthy people, with enhanced activity at lower glycemia. However, GIP stimulates glucagon secretion even at hyperglycemia in people with T2D, suggesting that inappropriate GIPR activity in α-cells contributes to the pathogenesis of T2D. Here, we review the literature describing GIP action and GIPR activity in the α-cell, detailing the basic science that has shaped the view of how GIP regulates glucagon secretion. We also contrast the effects of GIP on glucagon secretion in healthy and T2D people. Finally, we contextualize these observations in light of recent work that redefines the role of glucagon in glucose homeostasis, suggesting that hyperglucagonemia per se does not drive hyperglycemia. As new medications for T2D that incorporate GIPR activity are being developed, it is clear that a better understanding of GIPR activity beyond the β-cell is necessary. This work highlights the importance of focusing on the GIPR in α-cells.
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Affiliation(s)
| | - Jonathan E Campbell
- Duke Molecular Physiology Institute, USA; Department of Medicine, Division of Endocrinology, Duke University, Durham, NC, USA; Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, USA.
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Abstract
Controlling the excess and shortage of energy is a fundamental task for living organisms. Diabetes is a representative metabolic disease caused by the malfunction of energy homeostasis. The islets of Langerhans in the pancreas release long-range messengers, hormones, into the blood to regulate the homeostasis of the primary energy fuel, glucose. The hormone and glucose levels in the blood show rhythmic oscillations with a characteristic period of 5-10 min, and the functional roles of the oscillations are not clear. Each islet has [Formula: see text] and [Formula: see text] cells that secrete glucagon and insulin, respectively. These two counter-regulatory hormones appear sufficient to increase and decrease glucose levels. However, pancreatic islets have a third cell type, [Formula: see text] cells, which secrete somatostatin. The three cell populations have a unique spatial organization in islets, and they interact to perturb their hormone secretions. The mini-organs of islets are scattered throughout the exocrine pancreas. Considering that the human pancreas contains approximately a million islets, the coordination of hormone secretion from the multiple sources of islets and cells within the islets should have a significant effect on human physiology. In this review, we introduce the hierarchical organization of tripartite cell networks, and recent biophysical modeling to systematically understand the oscillations and interactions of [Formula: see text], [Formula: see text], and [Formula: see text] cells. Furthermore, we discuss the functional roles and clinical implications of hormonal oscillations and their phase coordination for the diagnosis of type II diabetes.
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Affiliation(s)
- Taegeun Song
- Department of Physics, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
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Dickerson MT, Dadi PK, Altman MK, Verlage KR, Thorson AS, Jordan KL, Vierra NC, Amarnath G, Jacobson DA. Glucose-mediated inhibition of calcium-activated potassium channels limits α-cell calcium influx and glucagon secretion. Am J Physiol Endocrinol Metab 2019; 316:E646-E659. [PMID: 30694690 PMCID: PMC6482666 DOI: 10.1152/ajpendo.00342.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Pancreatic α-cells exhibit oscillations in cytosolic Ca2+ (Ca2+c), which control pulsatile glucagon (GCG) secretion. However, the mechanisms that modulate α-cell Ca2+c oscillations have not been elucidated. As β-cell Ca2+c oscillations are regulated in part by Ca2+-activated K+ (Kslow) currents, this work investigated the role of Kslow in α-cell Ca2+ handling and GCG secretion. α-Cells displayed Kslow currents that were dependent on Ca2+ influx through L- and P/Q-type voltage-dependent Ca2+ channels (VDCCs) as well as Ca2+ released from endoplasmic reticulum stores. α-Cell Kslow was decreased by small-conductance Ca2+-activated K+ (SK) channel inhibitors apamin and UCL 1684, large-conductance Ca2+-activated K+ (BK) channel inhibitor iberiotoxin (IbTx), and intermediate-conductance Ca2+-activated K+ (IK) channel inhibitor TRAM 34. Moreover, partial inhibition of α-cell Kslow with apamin depolarized membrane potential ( Vm) (3.8 ± 0.7 mV) and reduced action potential (AP) amplitude (10.4 ± 1.9 mV). Although apamin transiently increased Ca2+ influx into α-cells at low glucose (42.9 ± 10.6%), sustained SK (38.5 ± 10.4%) or BK channel inhibition (31.0 ± 11.7%) decreased α-cell Ca2+ influx. Total α-cell Ca2+c was similarly reduced (28.3 ± 11.1%) following prolonged treatment with high glucose, but it was not decreased further by SK or BK channel inhibition. Consistent with reduced α-cell Ca2+c following prolonged Kslow inhibition, apamin decreased GCG secretion from mouse (20.4 ± 4.2%) and human (27.7 ± 13.1%) islets at low glucose. These data demonstrate that Kslow activation provides a hyperpolarizing influence on α-cell Vm that sustains Ca2+ entry during hypoglycemic conditions, presumably by preventing voltage-dependent inactivation of P/Q-type VDCCs. Thus, when α-cell Ca2+c is elevated during secretagogue stimulation, Kslow activation helps to preserve GCG secretion.
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Affiliation(s)
- Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - Molly K Altman
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - Kenneth R Verlage
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
- School of Medicine, Texas Tech University Health Sciences Center , Lubbock, Texas
- Department of Urology, Oregon Health and Science University , Portland, Oregon
| | - Ariel S Thorson
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - Kelli L Jordan
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
| | - Nicholas C Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
- Department of Neurobiology, Physiology and Behavior University of California , Davis, California
| | - Gautami Amarnath
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
- Experimental and Clinical Neurosciences, University of Regensburg , Regensburg , Germany
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University , Nashville, Tennessee
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14
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Zhang Y, Tang Z, Lin W, Yuan X, Jia J, Sun C, Li W. Molecular identification, tissue distribution and functional analysis of somatostatin receptors (SSTRs) in red-spotted grouper (Epinephelus akaara). Gen Comp Endocrinol 2019; 274:87-96. [PMID: 30654020 DOI: 10.1016/j.ygcen.2019.01.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 01/05/2019] [Accepted: 01/10/2019] [Indexed: 12/21/2022]
Abstract
In the present study, four full-length cDNAs of somatostatin receptor (sstr) were cloned from the forebrain and pituitary of red-spotted grouper. The four full-length cDNAs were designated 2292, 1522, 1873 and 1789 bp and identified as sstr1, sstr2, sstr3, and sstr5 by BLAST analysis; the corresponding sizes of the open reading frames (ORFs) were 1155, 1113, 1467 and 1503 bp, which encoding 384, 370, 488 and 500 aa, respectively. The four receptors have seven transmembrane structures and contain the YANSCANPI/VLY sequence, which is the conserved amino acid sequence of the SSTR family. A tissue distribution study showed that the four sstrs had different expression patterns, suggesting that they may play different roles in regulating different physiological processes. The four receptors mediate ERK1/2 phosphorylation by SS-14 in HEK293 cells, and SS-14 promotes ATK and ERK1/2 phosphorylation in primary hepatocytes of red-spotted grouper. These results facilitate the study of SSTRs-mediated intracellular signaling pathways.
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Affiliation(s)
- Yazhou Zhang
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Zimu Tang
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Weiru Lin
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Xi Yuan
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Jirong Jia
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Caiyun Sun
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Wensheng Li
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
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15
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Yamasaki T, Hirose H, Yamashita T, Takakura N, Morimoto S, Nakahata T, Kina A, Nakano Y, Okano Tamura Y, Sugama J, Odani T, Shimizu Y, Iwasaki S, Watanabe M, Maekawa T, Kasai S. Discovery of novel somatostatin receptor subtype 5 (SSTR5) antagonists: Pharmacological studies and design to improve pharmacokinetic profiles and human Ether-a-go-go-related gene (hERG) inhibition. Bioorg Med Chem 2017. [PMID: 28622905 DOI: 10.1016/j.bmc.2017.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Somatostatin (SST) is a peptide hormone comprising 14 or 28 amino acids that inhibits endocrine and exocrine secretion via five distinct G-protein-coupled receptors (SSTR1-5). SSTR5 has an important role in inhibiting the secretion of pancreatic and gastrointestinal hormones (e.g., insulin, GLP-1, PYY) through the binding of SSTs; hence, SSTR5 antagonists are expected to be novel anti-diabetic drugs. In the course of our lead generation program of SSTR5 antagonists, we have discovered a novel spiroazetidine derivative 3a. However, pharmacological evaluation of 3a revealed that it had to be administered at a high dose (100mg/kg) to show a persistent glucose-lowering effect in an oral glucose tolerance test (OGTT). We therefore initiated an optimization study based on 3a aimed at improving the antagonistic activity and mean residence time (MRT), resulting in the identification of 2-cyclopropyl-5-methoxybiphenyl derivative 3k. However, 3k did not show a sufficient persistent glucose-lowering effect in an OGTT; moreover, hERG inhibition was observed. Hence, further optimization study of the biphenyl moiety of compound 3k, focused on improving the pharmacokinetic (PK) profile and hERG inhibition, was conducted. Consequently, the introduction of a chlorine atom at the 6-position on the biphenyl moiety addressed a putative metabolic soft spot and increased the dihedral angle of the biphenyl moiety, leading to the discovery of 3p with an improved PK profile and hERG inhibition. Furthermore, 3p successfully exhibited a persistent glucose-lowering effect in an OGTT at a dose of 3mg/kg.
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Affiliation(s)
- Takeshi Yamasaki
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan.
| | - Hideki Hirose
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Tohru Yamashita
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Nobuyuki Takakura
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Sachie Morimoto
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Takashi Nakahata
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Asato Kina
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Yoshihide Nakano
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan; Global Procurement, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Yumiko Okano Tamura
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Jun Sugama
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Tomoyuki Odani
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Yuji Shimizu
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Shinji Iwasaki
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Masanori Watanabe
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Tsuyoshi Maekawa
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Shizuo Kasai
- Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
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16
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Hirose H, Yamasaki T, Ogino M, Mizojiri R, Tamura-Okano Y, Yashiro H, Muraki Y, Nakano Y, Sugama J, Hata A, Iwasaki S, Watanabe M, Maekawa T, Kasai S. Discovery of novel 5-oxa-2,6-diazaspiro[3.4]oct-6-ene derivatives as potent, selective, and orally available somatostatin receptor subtype 5 (SSTR5) antagonists for treatment of type 2 diabetes mellitus. Bioorg Med Chem 2017. [PMID: 28642028 DOI: 10.1016/j.bmc.2017.06.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Somatostatin receptor subtype 5 (SSTR5) has emerged as a novel attractive drug target for type 2 diabetes mellitus. Starting from N-benzyl azetidine derivatives 1 and 2 as in-house hit compounds, we explored the introduction of a carboxyl group into the terminal benzene of 1 to enhance SSTR5 antagonistic activity by the combination of the substituents at the 3-position of the isoxazoline. Incorporation of a carboxyl group at the 4-position of the benzene ring resulted in a significant enhancement in potency, however, the 4-benzoic acid derivative 10c exhibited moderate human ether-a-go-go related gene (hERG) inhibitory activity. A subsequent optimization study revealed that replacement of the 4-benzoic acid with an isonipecotic acid dramatically reduced hERG inhibition (5.6% inhibition at 30μM) by eliminating π-related interaction with hERG K+ channel, which resulted in the identification of 1-(2-((2,6-diethoxy-4'-fluorobiphenyl-4-yl)methyl)-5-oxa-2,6-diazaspiro[3.4]oct-6-en-7-yl)piperidin-4-carboxylic acid 25a (hSSTR5/mSSTR5 IC50=9.6/57nM). Oral administration of 25a in high-fat diet fed C57BL/6J mice augmented insulin secretion in a glucose-dependent manner and lowered blood glucose concentration.
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Affiliation(s)
- Hideki Hirose
- Research Division Medicinal Chemistry Laboratory, SCOHIA PHARMA, Inc., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan.
| | - Takeshi Yamasaki
- Research Division, Takeda Pharmaceutical Co., Ltd., Shonan Research Center, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Masaki Ogino
- Research Division Medicinal Chemistry Laboratory, SCOHIA PHARMA, Inc., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Ryo Mizojiri
- Research Division, Takeda Pharmaceutical Co., Ltd., Shonan Research Center, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Yumiko Tamura-Okano
- Research Division, Takeda Pharmaceutical Co., Ltd., Shonan Research Center, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Hiroaki Yashiro
- Research Division, Takeda Pharmaceutical Co., Ltd., Shonan Research Center, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Yo Muraki
- Research Division, Takeda Pharmaceutical Co., Ltd., Shonan Research Center, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Yoshihide Nakano
- Global Procurement, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Jun Sugama
- Research Division Medicinal Chemistry Laboratory, SCOHIA PHARMA, Inc., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Akito Hata
- Research Division, Takeda Pharmaceutical Co., Ltd., Shonan Research Center, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Shinji Iwasaki
- Research Division, Takeda Pharmaceutical Co., Ltd., Shonan Research Center, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Masanori Watanabe
- Research Division Medicinal Chemistry Laboratory, SCOHIA PHARMA, Inc., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Tsuyoshi Maekawa
- Research Division Medicinal Chemistry Laboratory, SCOHIA PHARMA, Inc., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Shizuo Kasai
- Research Division Medicinal Chemistry Laboratory, SCOHIA PHARMA, Inc., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
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17
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Swisa A, Avrahami D, Eden N, Zhang J, Feleke E, Dahan T, Cohen-Tayar Y, Stolovich-Rain M, Kaestner KH, Glaser B, Ashery-Padan R, Dor Y. PAX6 maintains β cell identity by repressing genes of alternative islet cell types. J Clin Invest 2016; 127:230-243. [PMID: 27941241 DOI: 10.1172/jci88015] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 10/13/2016] [Indexed: 12/19/2022] Open
Abstract
Type 2 diabetes is thought to involve a compromised β cell differentiation state, but the mechanisms underlying this dysfunction remain unclear. Here, we report a key role for the TF PAX6 in the maintenance of adult β cell identity and function. PAX6 was downregulated in β cells of diabetic db/db mice and in WT mice treated with an insulin receptor antagonist, revealing metabolic control of expression. Deletion of Pax6 in β cells of adult mice led to lethal hyperglycemia and ketosis that were attributed to loss of β cell function and expansion of α cells. Lineage-tracing, transcriptome, and chromatin analyses showed that PAX6 is a direct activator of β cell genes, thus maintaining mature β cell function and identity. In parallel, we found that PAX6 binds promoters and enhancers to repress alternative islet cell genes including ghrelin, glucagon, and somatostatin. Chromatin analysis and shRNA-mediated gene suppression experiments indicated a similar function of PAX6 in human β cells. We conclude that reduced expression of PAX6 in metabolically stressed β cells may contribute to β cell failure and α cell dysfunction in diabetes.
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18
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Liguz-Lecznar M, Urban-Ciecko J, Kossut M. Somatostatin and Somatostatin-Containing Neurons in Shaping Neuronal Activity and Plasticity. Front Neural Circuits 2016; 10:48. [PMID: 27445703 PMCID: PMC4927943 DOI: 10.3389/fncir.2016.00048] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/20/2016] [Indexed: 01/27/2023] Open
Abstract
Since its discovery over four decades ago, somatostatin (SOM) receives growing scientific and clinical interest. Being localized in the nervous system in a subset of interneurons somatostatin acts as a neurotransmitter or neuromodulator and its role in the fine-tuning of neuronal activity and involvement in synaptic plasticity and memory formation are widely recognized in the recent literature. Combining transgenic animals with electrophysiological, anatomical and molecular methods allowed to characterize several subpopulations of somatostatin-containing interneurons possessing specific anatomical and physiological features engaged in controlling the output of cortical excitatory neurons. Special characteristic and connectivity of somatostatin-containing neurons set them up as significant players in shaping activity and plasticity of the nervous system. However, somatostatin is not just a marker of particular interneuronal subpopulation. Somatostatin itself acts pre- and postsynaptically, modulating excitability and neuronal responses. In the present review, we combine the knowledge regarding somatostatin and somatostatin-containing interneurons, trying to incorporate it into the current view concerning the role of the somatostatinergic system in cortical plasticity.
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Affiliation(s)
- Monika Liguz-Lecznar
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology Warsaw, Poland
| | - Joanna Urban-Ciecko
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental BiologyWarsaw, Poland; Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon UniversityPittsburgh, PA, USA
| | - Malgorzata Kossut
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental BiologyWarsaw, Poland; Department of Psychology, University of Social Sciences and Humanities (SWPS)Warsaw, Poland
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19
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Lefèbvre PJ, Paquot N, Scheen AJ. Inhibiting or antagonizing glucagon: making progress in diabetes care. Diabetes Obes Metab 2015; 17:720-5. [PMID: 25924114 DOI: 10.1111/dom.12480] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 04/27/2015] [Accepted: 04/27/2015] [Indexed: 01/07/2023]
Abstract
Absolute or relative hyperglucagonaemia has been recognized for years in all experimental or clinical forms of diabetes. It has been suggested that excess secretion of glucagon by the islet α cells is a direct consequence of intra-islet insulin secretory defects. Recent studies have shown that knockout of the glucagon receptor or administration of a monoclonal specific glucagon receptor antibody make insulin-deficient type 1 diabetic rodents thrive without insulin. These observations suggest that glucagon plays an essential role in the pathophysiology of diabetes and that targeting the α cell and glucagon are innovative approaches in the management of diabetes. Despite active research and identification of promising compounds, no one selective glucagon antagonist is presently used in the treatment of diabetes. Interestingly, besides insulin, several drugs used today in the management of diabetes appear to exert their effects, in part, by inhibiting glucagon secretion (glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, α-glucosidase inhibitors and, possibly, sulphonylureas) or glucagon action (metformin). The potential risks associated with total glucagon suppression include α-cell hyperplasia, increased mass of the pancreas, increased susceptibility to hepatosteatosis and hepatocellular injury and increased risk of hypoglycaemia, and these should be considered in the search and development of new compounds reducing glucagon receptor signalling. More than 40 years after its initial description, hyperglucagonaemia in diabetes can no longer be ignored or minimized, and its correction represents an attractive way to improve diabetes management.
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Affiliation(s)
- P J Lefèbvre
- Division of Diabetes, Nutrition and Metabolic Disorders, Department of Medicine, University of Liège, Liège, Belgium
| | - N Paquot
- Division of Diabetes, Nutrition and Metabolic Disorders, Department of Medicine, University of Liège, Liège, Belgium
| | - A J Scheen
- Division of Diabetes, Nutrition and Metabolic Disorders, Department of Medicine, University of Liège, Liège, Belgium
- Division of Clinical Pharmacology, Department of Medicine, University of Liège, Liège, Belgium
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20
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Sun G, da Silva Xavier G, Gorman T, Priest C, Solomou A, Hodson DJ, Foretz M, Viollet B, Herrera PL, Parker H, Reimann F, Gribble FM, Migrenne S, Magnan C, Marley A, Rutter GA. LKB1 and AMPKα1 are required in pancreatic alpha cells for the normal regulation of glucagon secretion and responses to hypoglycemia. Mol Metab 2015; 4:277-86. [PMID: 25830091 PMCID: PMC4354920 DOI: 10.1016/j.molmet.2015.01.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 01/14/2015] [Accepted: 01/17/2015] [Indexed: 10/24/2022] Open
Abstract
AIMS/HYPOTHESIS Glucagon release from pancreatic alpha cells is required for normal glucose homoeostasis and is dysregulated in both Type 1 and Type 2 diabetes. The tumour suppressor LKB1 (STK11) and the downstream kinase AMP-activated protein kinase (AMPK), modulate cellular metabolism and growth, and AMPK is an important target of the anti-hyperglycaemic agent metformin. While LKB1 and AMPK have emerged recently as regulators of beta cell mass and insulin secretion, the role of these enzymes in the control of glucagon production in vivo is unclear. METHODS Here, we ablated LKB1 (αLKB1KO), or the catalytic alpha subunits of AMPK (αAMPKdKO, -α1KO, -α2KO), selectively in ∼45% of alpha cells in mice by deleting the corresponding flox'd alleles with a preproglucagon promoter (PPG) Cre. RESULTS Blood glucose levels in male αLKB1KO mice were lower during intraperitoneal glucose, aminoimidazole carboxamide ribonucleotide (AICAR) or arginine tolerance tests, and glucose infusion rates were increased in hypoglycemic clamps (p < 0.01). αLKB1KO mice also displayed impaired hypoglycemia-induced glucagon release. Glucose infusion rates were also elevated (p < 0.001) in αAMPKα1 null mice, and hypoglycemia-induced plasma glucagon increases tended to be lower (p = 0.06). Glucagon secretion from isolated islets was sensitized to the inhibitory action of glucose in αLKB1KO, αAMPKdKO, and -α1KO, but not -α2KO islets. CONCLUSIONS/INTERPRETATION An LKB1-dependent signalling cassette, involving but not restricted to AMPKα1, is required in pancreatic alpha cells for the control of glucagon release by glucose.
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Affiliation(s)
- Gao Sun
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, UK
| | - Gabriela da Silva Xavier
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, UK
| | | | | | - Antonia Solomou
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, UK
| | - David J. Hodson
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, UK
| | - Marc Foretz
- Inserm, U1016, Institut Cochin, Paris, France
- CNRS, UMR8104, Paris, France
- Université Paris Descartes, Sorbonne Paris cité, Paris, France
| | - Benoit Viollet
- Inserm, U1016, Institut Cochin, Paris, France
- CNRS, UMR8104, Paris, France
- Université Paris Descartes, Sorbonne Paris cité, Paris, France
| | - Pedro-Luis Herrera
- Department of Genetic Medicine & Development, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Helen Parker
- Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge, UK
| | - Frank Reimann
- Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge, UK
| | - Fiona M. Gribble
- Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge, UK
| | - Stephanie Migrenne
- University Paris Diderot-Paris 7-Unit of Functional and Adaptive Biology (BFA) EAC 7059C NRS, France
| | - Christophe Magnan
- University Paris Diderot-Paris 7-Unit of Functional and Adaptive Biology (BFA) EAC 7059C NRS, France
| | | | - Guy A. Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, UK
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21
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Rutter GA, Hodson DJ. Minireview: intraislet regulation of insulin secretion in humans. Mol Endocrinol 2013; 27:1984-95. [PMID: 24243488 PMCID: PMC5426601 DOI: 10.1210/me.2013-1278] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 10/23/2013] [Indexed: 12/25/2022] Open
Abstract
The higher organization of β-cells into spheroid structures termed islets of Langerhans is critical for the proper regulation of insulin secretion. Thus, rodent β-cells form a functional syncytium that integrates and propagates information encoded by secretagogues, producing a "gain-of-function" in hormone release through the generation of coordinated cell-cell activity. By contrast, human islets possess divergent topology, and this may have repercussions for the cell-cell communication pathways that mediate the population dynamics underlying the intraislet regulation of insulin secretion. This is pertinent for type 2 diabetes mellitus pathogenesis, and its study in rodent models, because environmental and genetic factors may converge on these processes in a species-specific manner to precipitate the defective insulin secretion associated with glucose intolerance. The aim of the present minireview is therefore to discuss the structural and functional underpinnings that influence insulin secretion from human islets, and the possibility that dyscoordination between individual β-cells may play an important role in some forms of type 2 diabetes mellitus.
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Affiliation(s)
- Guy A Rutter
- Section Cell Biology, Department of Medicine, Imperial College London, London SW7 2AZ, United Kingdom. ; or Professor Guy A. Rutter, Section of Cell Biology, Department of Medicine, Imperial College London, London SW7 2AZ, United Kingdom. E-mail:
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Kunjara S, Greenbaum AL, McLean P, Grønbaek H, Flyvbjerg A. Effects of long-term experimental diabetes on adrenal gland growth and phosphoribosyl pyrophosphate formation in growth hormone-deficient dwarf rats. Int J Exp Pathol 2012; 93:196-201. [PMID: 22583133 DOI: 10.1111/j.1365-2613.2012.00818.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The availability of growth hormone (GH)-deficient dwarf rats with otherwise normal pituitary function provides a powerful tool to examine the relative role of hyperglycaemia and the reordering of hormonal factors in the hypertrophy-hyperfunction of the adrenal gland that is seen in experimental diabetes. Here, we examine the effects of long-term (6 months) experimental diabetes on the growth of the adrenal glands; their content of phosphoribosyl pyrophosphate (PRPP); and the activity of the PRPP synthetase, G6P dehydrogenase and 6PG dehydrogenase enzymes in GH-deficient dwarf rats compared to heterozygous controls. These parameters were selected in view of the known role of PRPP in both de novo and salvage pathways of purine and pyrimidine synthesis and in the formation of NAD, and in view of the role of the oxidative enzymes of the pentose phosphate pathway in both R5P formation and the generation of the NADPH that is required in reductive synthetic reactions. This study shows that GH deficiency prevents the increase in adrenal gland weight, PRPP synthetase, PRPP content and G6P dehydrogenase and 6PG dehydrogenase. This contrasts sharply with the heterozygous group that showed the expected increase in these parameters. The blood glucose levels of the groups of long-term diabetic rats, both GH-deficient and heterozygous, remained at an elevated level throughout the experiment. These results are fully in accord with earlier evidence from studies with somatostatin analogues which showed that the GH-insulin-like growth factor I (IGF-I)-axis plays a key role in the adrenal diabetic hypertrophy-hyperfunction syndrome.
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Affiliation(s)
- Sirilaksana Kunjara
- Division of Biosciences, Research Department of Cell and Development Biology, University College London, Gower Street, London WC1E 6BT, UK
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Kunjara S, Greenbaum AL, Sochor M, Ali M, Flyvbjerg A, Grønbaek H, McLean P. Effects of long-acting somatostatin analogues on adrenal growth and phosphoribosyl pyrophosphate formation in experimental diabetes. Int J Exp Pathol 2012; 93:56-69. [PMID: 22264286 DOI: 10.1111/j.1365-2613.2011.00801.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Adrenal growth and increased adrenal function occur in experimental diabetes. Previously, we have shown that phosphoribosyl pyrophosphate (PRPP) and PRPP synthetase increased rapidly between 3 and 7 days after induction of diabetes with streptozotocin (STZ), with less marked changes in enzymes of the pentose phosphate pathway. The present study examines the earlier phase of 1-3 days following induction of diabetes, seeking to elucidate whether control of PRPP production is a result of diabetic hyperglycaemia, or to a more general re-ordering of hormonal factors. To investigate this question, the role of insulin and two different long-acting somatostatin analogues, Angiopeptin and Sandostatin, were used in a well-established animal model. PRPP was chosen specifically as a target for these studies in view of its central role in nucleotide formation and nicotinamide mononucleotide synthesis via Nampt which is the rate-limiting step in the synthesis of NAD and which has been shown to have multiple roles in cell signalling in addition to its known function in glycolysis and energy production. Treatment with the somatostatin analogues ab initio effectively abolished the adrenal growth, the increase in PRPP formation and the rise of PRPP synthetase activity in the first 7 days of diabetes, without having any significant effect on blood glucose values. This suggests that elevated glucose per se is not responsible for the diabetic adrenal hypertrophy and implies that growth factors/hormones, regulated by somatostatin analogues, play a significant role in adrenal growth processes.
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Affiliation(s)
- Sirilaksana Kunjara
- Division of Biosciences, Metabolic Regulation Group, University College London, Gower Street, London, UK
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da Silva Xavier G, Farhan H, Kim H, Caxaria S, Johnson P, Hughes S, Bugliani M, Marselli L, Marchetti P, Birzele F, Sun G, Scharfmann R, Rutter J, Siniakowicz K, Weir G, Parker H, Reimann F, Gribble FM, Rutter GA. Per-arnt-sim (PAS) domain-containing protein kinase is downregulated in human islets in type 2 diabetes and regulates glucagon secretion. Diabetologia 2011; 54:819-27. [PMID: 21181396 PMCID: PMC3052475 DOI: 10.1007/s00125-010-2010-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 11/12/2010] [Indexed: 10/27/2022]
Abstract
AIMS/HYPOTHESIS We assessed whether per-arnt-sim (PAS) domain-containing protein kinase (PASK) is involved in the regulation of glucagon secretion. METHODS mRNA levels were measured in islets by quantitative PCR and in pancreatic beta cells obtained by laser capture microdissection. Glucose tolerance, plasma hormone levels and islet hormone secretion were analysed in C57BL/6 Pask homozygote knockout mice (Pask-/-) and control littermates. Alpha-TC1-9 cells, human islets or cultured E13.5 rat pancreatic epithelia were transduced with anti-Pask or control small interfering RNAs, or with adenoviruses encoding enhanced green fluorescent protein or PASK. RESULTS PASK expression was significantly lower in islets from human type 2 diabetic than control participants. PASK mRNA was present in alpha and beta cells from mouse islets. In Pask-/- mice, fasted blood glucose and plasma glucagon levels were 25 ± 5% and 50 ± 8% (mean ± SE) higher, respectively, than in control mice. At inhibitory glucose concentrations (10 mmol/l), islets from Pask-/- mice secreted 2.04 ± 0.2-fold (p < 0.01) more glucagon and 2.63 ± 0.3-fold (p < 0.01) less insulin than wild-type islets. Glucose failed to inhibit glucagon secretion from PASK-depleted alpha-TC1-9 cells, whereas PASK overexpression inhibited glucagon secretion from these cells and human islets. Extracellular insulin (20 nmol/l) inhibited glucagon secretion from control and PASK-deficient alpha-TC1-9 cells. PASK-depleted alpha-TC1-9 cells and pancreatic embryonic explants displayed increased expression of the preproglucagon (Gcg) and AMP-activated protein kinase (AMPK)-alpha2 (Prkaa2) genes, implying a possible role for AMPK-alpha2 downstream of PASK in the control of glucagon gene expression and release. CONCLUSIONS/INTERPRETATION PASK is involved in the regulation of glucagon secretion by glucose and may be a useful target for the treatment of type 2 diabetes.
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Affiliation(s)
- G. da Silva Xavier
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ UK
| | - H. Farhan
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ UK
| | - H. Kim
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ UK
| | - S. Caxaria
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ UK
| | - P. Johnson
- Nuffield Department of Surgical Sciences, Oxford University, Oxford, UK
| | - S. Hughes
- Nuffield Department of Surgical Sciences, Oxford University, Oxford, UK
| | - M. Bugliani
- Dipartimento di Endocrinologia e Metabolismo, Unità Metabolica, Università di Pisa, Pisa, Italy
| | - L. Marselli
- Dipartimento di Endocrinologia e Metabolismo, Unità Metabolica, Università di Pisa, Pisa, Italy
| | - P. Marchetti
- Dipartimento di Endocrinologia e Metabolismo, Unità Metabolica, Università di Pisa, Pisa, Italy
| | - F. Birzele
- Boehringer Ingelheim Pharma, Target Discovery Research, Ingelheim, Germany
| | - G. Sun
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ UK
| | - R. Scharfmann
- INSERM U845, Centre de Recherche Croissance et Signalisation, Université Paris Descartes, Faculté de Médecine, Hôpital Necker, Paris, France
| | - J. Rutter
- Division of Endocrinology, University of Utah School of Medicine, Salt Lake, UT USA
| | - K. Siniakowicz
- Section on Islet Transplantation and Cell Biology, Research Division, Joslin Diabetes Center and the Department of Medicine, Harvard Medical School, Boston, MA USA
| | - G. Weir
- Section on Islet Transplantation and Cell Biology, Research Division, Joslin Diabetes Center and the Department of Medicine, Harvard Medical School, Boston, MA USA
| | - H. Parker
- Cambridge Institute for Medical Research and Department of Clinical Biochemistry, Addenbrooke’s Hospital, Cambridge, UK
| | - F. Reimann
- Cambridge Institute for Medical Research and Department of Clinical Biochemistry, Addenbrooke’s Hospital, Cambridge, UK
| | - F. M. Gribble
- Cambridge Institute for Medical Research and Department of Clinical Biochemistry, Addenbrooke’s Hospital, Cambridge, UK
| | - G. A. Rutter
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Exhibition Road, South Kensington, London, SW7 2AZ UK
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Riboulet-Chavey A, Diraison F, Siew LK, Wong FS, Rutter GA. AMP-activated protein kinase regulates glucagon secretion from mouse pancreatic alpha cells. Diabetologia 2011; 54:125-34. [PMID: 20938634 PMCID: PMC6101198 DOI: 10.1007/s00125-010-1929-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Accepted: 09/01/2010] [Indexed: 10/19/2022]
Abstract
AIM/HYPOTHESIS AMP-activated protein kinase (AMPK), encoded by Prkaa genes, is emerging as a key regulator of overall energy homeostasis and the control of insulin secretion and action. We sought here to investigate the role of AMPK in controlling glucagon secretion from pancreatic islet alpha cells. METHODS AMPK activity was modulated in vitro in clonal alphaTC1-9 cells and isolated mouse pancreatic islets using pharmacological agents and adenoviruses encoding constitutively active or dominant negative forms of AMPK. Glucagon secretion was measured during static incubation by radioimmunoassay. AMPK activity was assessed by both direct phosphotransfer assay and by western (immuno-)blotting of the phosphorylated AMPK α subunits and the downstream target acetyl-CoA carboxylase 1. Intracellular free [Ca²(+)] was measured using Fura-Red. RESULTS Increasing glucose concentrations strongly inhibited AMPK activity in clonal pancreatic alpha cells. Forced increases in AMPK activity in alphaTC1-9 cells, achieved through the use of pharmacological agents including metformin, phenformin and A-769662, or via adenoviral transduction, resulted in stimulation of glucagon secretion at both low and high glucose concentrations, whereas AMPK inactivation inhibited both [Ca²(+)](i) increases and glucagon secretion at low glucose. Transduction of isolated mouse islets with an adenovirus encoding AMPK-CA under the control of the preproglucagon promoter increased glucagon secretion selectively at elevated glucose concentrations. CONCLUSIONS/INTERPRETATION AMPK is strongly regulated by glucose in pancreatic alpha cells, and increases in AMPK activity are sufficient and necessary for the stimulation of glucagon release in vitro. Modulation of AMPK activity in alpha cells may therefore provide a novel approach to controlling blood glucose concentrations.
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Affiliation(s)
- Audrey Riboulet-Chavey
- Department of Cell Biology, Division of Medicine, Sir Alexander Fleming Building, Imperial College, London, Exhibition Road, London SW7 2AZ, UK
| | - Frédérique Diraison
- Department of Cell Biology, Division of Medicine, Sir Alexander Fleming Building, Imperial College, London, Exhibition Road, London SW7 2AZ, UK
| | - L. Khai Siew
- Dept. of Cellular & Molecular Medicine, University of Bristol, School of Medical Sciences, Bristol, BS8 1TD, UK
| | - F. Susan Wong
- Dept. of Cellular & Molecular Medicine, University of Bristol, School of Medical Sciences, Bristol, BS8 1TD, UK
| | - Guy A. Rutter
- Department of Cell Biology, Division of Medicine, Sir Alexander Fleming Building, Imperial College, London, Exhibition Road, London SW7 2AZ, UK
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Kelly C, Flatt PR, McClenaghan NH. Cell-to-cell communication and cellular environment alter the somatostatin status of delta cells. Biochem Biophys Res Commun 2010; 399:162-6. [PMID: 20637727 DOI: 10.1016/j.bbrc.2010.07.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Accepted: 07/12/2010] [Indexed: 11/17/2022]
Abstract
INTRODUCTION Somatostatin, released from pancreatic delta cells, is a potent paracrine inhibitor of insulin and glucagon secretion. Islet cellular interactions and glucose homeostasis are essential to maintain normal patterns of insulin secretion. However, the importance of cell-to-cell communication and cellular environment in the regulation of somatostatin release remains unclear. METHODS This study employed the somatostatin-secreting TGP52 cell line maintained in DMEM:F12 (17.5mM glucose) or DMEM (25mM glucose) culture media. The effect of pseudoislet formation and culture medium on somatostatin content and release in response to a variety of stimuli was measured by somatostatin EIA. In addition, the effect of pseudoislet formation on cellular viability (MTT and LDH assays) and proliferation (BrdU ELISA) was determined. RESULTS TGP52 cells readily formed pseudoislets and showed enhanced functionality in three-dimensional form with increased E-cadherin expression irrespective of the culture environment used. However, culture in DMEM decreased cellular somatostatin content (P<0.01) and increased somatostatin secretion in response to a variety of stimuli including arginine, calcium and PMA (P<0.001) when compared with cells grown in DMEM:F12. Configuration of TGP52 cells as pseudoislets reduced the proliferative rate and increased cellular cytotoxicity irrespective of culture medium used. CONCLUSIONS Somatostatin secretion is greatly facilitated by cell-to-cell interactions and E-cadherin expression. Cellular environment and extracellular glucose also significantly influence the function of delta cells.
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Affiliation(s)
- Catriona Kelly
- SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, UK.
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Soria B, Tudurí E, González A, Hmadcha A, Martin F, Nadal A, Quesada I. Pancreatic islet cells: a model for calcium-dependent peptide release. HFSP JOURNAL 2010; 4:52-60. [PMID: 20885773 DOI: 10.2976/1.3364560] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 02/25/2010] [Indexed: 11/19/2022]
Abstract
In mammals the concentration of blood glucose is kept close to 5 mmol∕l. Different cell types in the islet of Langerhans participate in the control of glucose homeostasis. β-cells, the most frequent type in pancreatic islets, are responsible for the synthesis, storage, and release of insulin. Insulin, released with increases in blood glucose promotes glucose uptake into the cells. In response to glucose changes, pancreatic α-, β-, and δ-cells regulate their electrical activity and Ca(2+) signals to release glucagon, insulin, and somatostatin, respectively. While all these signaling steps are stimulated in hypoglycemic conditions in α-cells, the activation of these events require higher glucose concentrations in β and also in δ-cells. The stimulus-secretion coupling process and intracellular Ca(2+) ([Ca(2+)](i)) dynamics that allow β-cells to secrete is well-accepted. Conversely, the mechanisms that regulate α- and δ-cell secretion are still under study. Here, we will consider the glucose-induced signaling mechanisms in each cell type and the mathematical models that explain Ca(2+) dynamics.
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Braun M, Ramracheya R, Amisten S, Bengtsson M, Moritoh Y, Zhang Q, Johnson PR, Rorsman P. Somatostatin release, electrical activity, membrane currents and exocytosis in human pancreatic delta cells. Diabetologia 2009; 52:1566-78. [PMID: 19440689 DOI: 10.1007/s00125-009-1382-z] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 04/09/2009] [Indexed: 01/24/2023]
Abstract
AIMS/HYPOTHESIS The aim of this study was to characterise electrical activity, ion channels, exocytosis and somatostatin release in human delta cells/pancreatic islets. METHODS Glucose-stimulated somatostatin release was measured from intact human islets. Membrane potential, currents and changes in membrane capacitance (reflecting exocytosis) were recorded from individual human delta cells identified by immunocytochemistry. RESULTS Somatostatin secretion from human islets was stimulated by glucose and tolbutamide and inhibited by diazoxide. Human delta cells generated bursting or sporadic electrical activity, which was enhanced by tolbutamide but unaffected by glucose. Delta cells contained a tolbutamide-insensitive, Ba(2+)-sensitive inwardly rectifying K(+) current and two types of voltage-gated K(+) currents, sensitive to tetraethylammonium/stromatoxin (delayed rectifying, Kv2.1/2.2) and 4-aminopyridine (A current). Voltage-gated tetrodotoxin (TTX)-sensitive Na(+) currents contributed to the action potential upstroke but TTX had no effect on somatostatin release. Delta cells are equipped with Ca(2+) channels blocked by isradipine (L), omega-agatoxin (P/Q) and NNC 55-0396 (T). Blockade of any of these channels interferes with delta cell electrical activity and abolishes glucose-stimulated somatostatin release. Capacitance measurements revealed a slow component of depolarisation-evoked exocytosis sensitive to omega-agatoxin. CONCLUSIONS/INTERPRETATION Action potential firing in delta cells is modulated by ATP-sensitive K(+)-channel activity. The membrane potential is stabilised by Ba(2+)-sensitive inwardly rectifying K(+) channels. Voltage-gated L- and T-type Ca(2+) channels are required for electrical activity, whereas Na(+) currents and P/Q-type Ca(2+) channels contribute to (but are not necessary for) the upstroke of the action potential. Action potential repolarisation is mediated by A-type and Kv2.1/2.2 K(+) channels. Exocytosis is tightly linked to Ca(2+)-influx via P/Q-type Ca(2+) channels. Glucose stimulation of somatostatin secretion involves both K(ATP) channel-dependent and -independent processes.
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Affiliation(s)
- M Braun
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford OX37 LJ, UK.
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